Privacy is a myth
First of all, if privacy is your only concern, nothing is going to change for you. Most of us probably, already have other Facebook apps like Facebook, Messenger, or Instagram. If that is the case with you, nothing will change because you are already sharing way more data than WhatsApp.
Apart from Facebook apps, we have several other apps, which collect a lot of information from our devices than WhatsApp collects. It is not a big deal.
Remember, once you are connected to the internet and shared something over the internet, it is no longer private. Privacy is a myth when we are talking about the internet.
Are your messages safe?
Can you verify the end-to-end encryption of WhatsApp?
NO! Currently, there is no way to verify if WhatsApp’s chats are end-to-end encrypted or not. Unlike apps like Signal, Telegram, etc., WhatsApp’s code is proprietary and not open for public audits. So, in the case of end-to-end encryption, we have to trust whatever Facebook is saying.
(Story in progress)